[xep-support] multi threaded access issue ?

Rob Stote RStote at whitehilltech.com
Mon Feb 6 10:34:11 PST 2006


Thanks David, but I don't believe Garbage collection is the issue. When I
disable the hyper-threading on the HT box I get an increase in performance
given the same number of threads (2). As when the Hyper-Threading was
enabled. Further, our second test machine, the 2 CPU, box is an extremley
powerful machine, both CPUs are Dual core Xeon, in excess of  3.0 Ghz each.
I have 2 Gigs of Ram on this box and the heap size is set to 1 Gig. During
memory analysis I have seen that my memeory usage "peaked" at apx 198MB, no
where close to the 1 Gig Limit I have set. 

Thanks again

Rob

-----Original Message-----
From: owner-xep-support at renderx.com [mailto:owner-xep-support at renderx.com]
On Behalf Of David Tolpin
Sent: Monday, February 06, 2006 11:52 AM
To: xep-support at renderx.com
Subject: Re: [xep-support] multi threaded access issue ?

> Any ideas as to why this is happening ?
>

When you run multiple threads on the same machine with the same memory
limit, you get much more memory use. Garbage collector in JVM is 'stop the
world' by default. This means that with increased memory churning you spend
more time in all the threads waiting for the garbage collector to complete
(which has low priority, by the way).

You need also four times more memory and/or ParallelGC enable to benefit
from multiple threads.

David Tolpin
 
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